thank you clive, i never paid any attention to my plugs in my home until i seen this video, so i went around & found 3 of my plugs had a sleeve on the earth pin, all of which was a metal case appliance, now all the plugs are changed! thank you again clive!
It's good to live in a country with proper Schuko, where something like this can't happen. But, you almost are unable to unplug Schuko plugs... This is really annoying... They're so stiff!
The one advantage of the UK plug is the safety of it. Built in fuse, shuttering etc, although you can get those on the other regions units too, but they are only optional and not a standard like the UK plugs. Will we ever see a world standardisation of plug sockets some day? Taking the best features of each, or is it just too late for that?
Schuko also has shutters and safety. We don't need a fuse in each plug cause we don't need to have a 32 Amps ring mains cause we can actually afford copper. xP But as I said, it's hard to remove them out of sockets which really sucks and they aren't polarized... But also your UK ones are far too bulky...
@Allanda1 I never experienced that in Germany. But it happened to my ex gf back then after some years of tear on the same socket. I fixed it, though. It now can survive tanks pulling on it. ;)
The power MOSFET at the secondary side actually regulates the output linearly. The SMPS always delivers just a few more volts than what's the output voltage. Bench power supplies are usually built like this. This allows efficiency of a SMPS but also the supreme regulation ability of a linear regulator. So it is very efficient and yet it has very little ripple and very fast current limiting.
I come from the land of different plugs (not the type bigclive uses), but this really just seems like bad socket design. Can someone explain why the socket itself is only designed to contact half of the earth pin and not the entire length? (I'm guessing cost, but maybe something else?)
linagee it's an illegal plug in UK. As Clive said it is the Chinese design that's wrong not the socket. A good plug don't need to be contacted for the entire length of the earth pin
@@linagee I think most electricians would say the UK has the best plug design in terms of safety and utility. The only real drawback is that it's very large, which is quite inconvenient.
Howdy Clive, I've been using a PSU similar to that one there for a few months now. Your vid motivated me to pop it open and have a look. Am I glad I did! The earth wire from the mains cable has a ring terminal on it, and the screw through that into the chassis was in by only three turns or so. Riiight. The terminal was flopping around on the screw. THANK YOU sir!
This reminds me of a control panel I saw at the local scrap yard, just a Chinese who-flung-dung machine cabinet with 3 ABB OEM VFDs inside (10 - 25 and probably 50Hp) and it looks like the crappy conductors they used to go into the 25HP drive got quite hot and started arcing, they probably were never torqued down to mfg specs either. needless to say the whole panel was carbon black inside and all drives and PLC gear were destroyed by heat and smoke :(
To add; if you encounter illegal/ dangerous cable like that, don't throw it away. First, cut it near the base of the cable on the end that is faulty. Then throw it to trash. Don't let anyone think it is just thrown away and still works. It was hard to get used to that when i used my own cables to the death but really, protecting public is #1 priority. Destroy or disable dangerous equipment, don't rely on post-it-notes or memory or common sense. Even if it is marked "don't touch, will give you aids, ebola and explode" and it is in a trash, some moron will dig it out if it "looks alrite to me".. Take fuses out, cut cords, use hammers and saws.
When a piece of hardware is flakey, I try to loan it to someone I don't like. If and when they complain about it I say "I don't know man, it was working ok before. You must have dropped it. That's an expensive piece of hardware, let me find out how much it costs". Just a joke, I only did this once with a hard drive. I did not charge them. I would not do this with a dangerous item.
Another superbly informative video from Clive. I'm a retired professional electronic engineer, but I still learn something new from most of Clive's videos. I bought a similar, but not quite identical PSU from Amazon recently and was pleased to note that it doesn't have the same partially sleeved mains plug.
There is a subtle problem with the secondary small PSU in there. Does it have its own fuse? Probably not.. it means the large main fuse is protecting it. But this large fuse is too big for the secondary PSU. If this secondary PSU fails, the main fuse probably won't blow. Instead the secondary PSU catches fire, pops, smokes. Many PC power supplies have this same issue with their always on 5V "standby" supply.
You bring up a very good question. The second or standby PSU, and what size fuse should protect the mains power cord from overload? If the PSU is designed properly, there should be a link that will evaporate if 200% of the current is pulled for 1 second. So, then is there a pico fuse in series with the mains voltage going to the alternate power supply. perhaps not. Now all 'standby' PSUs need to be checked. Lets have a Royal Enquiry! must be Tony Blair's fault...... {lol).
Your right or left hand has a finger on it that clicked a button. Some garden scissors and a bit of jest should remove the source of the problems. Might have to repeat 9 times to achieve more robust results.
I bought a STP3010 (Sky Top Power) p/s just like this one, in Feb 2016. It had a fault (diode in the fan supply burnt out). Most likely from a track nearby touching a bit of solder under a filter cap. Easily fixed after the company gave me a portion of the circuit to look at. Other than that, I tightened the binding post nuts (steel - naughty!), glued a bit of fibreglass pcb across the heatsinks so the they could be used to lift the whole pcb assembly. Put a warning note on the heatsinks (240V). Also positioned a business card so the fan drew more air from the heatsink area, and scraped the earth connection at the frame. And attached a handle for carrying. Checked output using 4 Ohm (bit if steel wire in a glass of water) periodically paralleled with 12 Ohm. No evidence of ringing on my (cheap) CRO. No problems since then.
Better than the heatsink compound trick is a UV reactive dye and blacklight. What I use was originally meant for crack detection of some kind and looks like a crayon however it contains a bright orange/red UV reactive dye. You basically rub the crayon over a surface and shine a UV torch on it and the lettering lights up (and any surface imperfections/cracks). The crayon itself is normally enough on it's own (it's a light colour) however the UV light makes it completely visible no matter the lighting conditions (it also allows pictures to be taken very easily as the lettering actually emits light).
Yep, as I guessed on the last video: the connector gets very hot because of chincy plugs and wires. Overall the circuit doesn't look bad. Line filtering, chunky components and heatsinks, thermal cutout are nice. Seems to be a proper design (except for the weird thing with the current regulation). The overall build quality lets it down again though. Crooked components, big inductor only "secured" with a zip tie, one of the front panel wires so short it tugs on the connector, bad connections to the binding posts (at least some here have reported that) and of course the really dangerous wires they supplied with it (both of them, mains and secondary). Given the price this is a PSU that beginners will buy, who at the same time very likely will not know how to spot a dangerous product and how to fix it. That's worrying.
superdau In the zip ties defense, a lot of modern cars have them holding the wiring looms together/in place. Chrysler loves em as I'm sure some others do. If they can handle the heat/cold cycles and vibration of the engine and road, I'd think an inductor is little worry. But how you use them is just as important as where you use them. I mean, the mounting isn't great, really shouldn't be a big deal for something that hides in the corner of a bench.
superdau actually I’m just getting to the end of the video, is there a couple of mods that can be done that would make this unit decent? Forgive me I don’t entirely understand all the lingo but will learn whatever needed to make appropriate mods. I caught the bit about soldering the leads, but looks like I missed some others
ForestCat_Peter "I got sent one of those bastard mains cables from ebay. The resistance of each conductor is over 1 ohm - should be milli-ohms, they are DANGEROUS" Why not tell Trading-Standards? Of course it depends where it was sent-from. If from a seller in the UK, they need a roasting. Perhaps placed handcuffed to a chair surrounded by a number of their devices that are set to self-destruct with such dodgy mains leads. If from abroad, say via Ebay or Amazon, then they need to crack-down on the sellers, but there's not much else TS can do with overseas suppliers.
Never will understand why test eqpt companies skimp on leads. We just paid several thousand pounds for an 8 1/2 digit bench multimeter for our lab at work from a very reputable British manufacturer. The meter itself is top-notch. The leads that came with it were about as good as the ones seen here. Luckily we use our own in-house made leads anyway.
Thank you. I think I have this power supply and will check on the leads and the mains cable. It is amazing how a device can be made so vulnerable by these leads and the supply cord - which I will check. I often use my own power leads.
Was doing a bit of electrolysis on some old tools with the exact same power supply. For once I moved all outside to avoid any building up of hydrogen in the workshop and it was a good thing. I'm guessing about 10 minutes in I was greeted with a full on fire 7 feet tall just managed to pull the plug and dumped the bucket of electrolysis solution tools and all before my went up. Being one with a guilty conscience I just assumed that I did something stupid and most times that is a safe bet. Just looked at the burned remains of it. The control panel is melted and hanging open and can see no damage on the inside and very little damage on the backside of the control panel so yes I believe you are %100 correct about the connectors on the front. I've been a subscriber of yours long before I almost burned my house down and watch plenty of UA-cam videos before buying this power supply and still some how overlooked this vid
Clive, have you ever had a look at a PSU for a desktop computer? I tried searching the channel, but didn't see one. Popular wisdom in the PC building community is that you should never cheap out on your power supply. Anecdotes I have read include: they'll fry your other components, electrocute anyone who touches the case, blow up under moderate usage, or set your house afire. I'd be interested to know if there's truth to that. I'm sure there are cheap, shitty ATX power supplies from China, just waiting to unleash hell...
That is a fun thing to learn the hard way lol. Making prototypes of stuff figure hey aluminum foil could take an option I didn't have place... nope lol. I have solder nickels and pennies together solder sculpting with crap solder yet aluminum foil is quite rude.
I have one. It failed quite spectacularly due to a bad IRF840. There was a dramatic jump in stability after the repair. It started to go into thermal runaway when the fet popped. If I hadn't been there, it would have been a disaster. NOTE: replace the fine voltage pot. A bad run of them was used on this model! I used a 10 turn precision pot and now setting this beast no longer pisses me off.
Glad I saw this. This is the power supply I bought as I am a beginner with electronics and the price was tenable. I had my doubts but I'm glad to see at least the power supply itself is robust.
Excellent video Clive. I love your teardowns and reviews. One learns a lot from you. I always undo my cables also. The ones that are screwed in I always twist, fold then solder to make sure that the screw bites in solidly. I know that the solder has a low melting point but I figure that there would be less resistance in the connection this way and therefore a lower chance of the banana plugs heating up.
It is not good to solder stranded wire in a screwed terminal. The solder compresses and the connection comes loose. Maybe some types of terminal blocks are ok but it is still not the best way. A couple of cow orkers where I used to work did this on a junction box for a hydraulic pump and the wires came loose with the vibration. This caused an emergency shut down on the gas turbine which is not a nice thing to do.
Thanks for this video Clive! I have a similar PSU and re-soldered the leads but before I did that I checked the resistance with my Fluke 23 at about 0.9 ohms. After modifying the leads the resistance was a more sensible 0.2 ohms.
Thanks Clive, came to this a bit late. Have a Lavolta model of this PSU and happy to report the cables are Good. Mains plug full earth pin and output cables all soldered connections to the crocks and the end of the cable is solder tinned and clamped. Wire is very thick and difficult to bend. Had a fault where the protection diode across the output went S/C so had replace that.
I found the 'convenient' spinny feature on the banana plug to just lose continuity, so I had to solder across the slip-ring. To do this, once you take out the set-screw, the plastic piece just slides off, making for easily soldering the metal part, and losing all the pieces. Then for the lead wire, something like 18 awg or 1mm, folded back onto itself 3 times and twisted, then tin it (make it shiny with solder), allowed the screw to dig in and make a nice connection regardless of radial orientation. Thanks for the video!
Thanks for the bit about testing for copper coated aluminium. I retired as an electronics tech from the US Navy in '93 and I don't remember that particular trick in our training, but then again I guess most of our stuff was procured under pretty tight contract overview so I don't think we would have run into it very often.
Very interesting point about the insulated earth pin and something I had not realized or looked out for before, on a related point I recently bought a Chinese aquarium heater which came with a UK style square pin molded plug which looked strange because it was very small, but fitted the socket OK, however the plug did not have a fuse or facility to fit one. "UK plug" looks like a reason to buy on Ebay, but non compliant UK plug , probably not.
I have one of these supplies. I had trouble with heat and found the terminal back plate was not tight enough. I also ran a SSTC at 31 volts and nearly 10 amps via two TIP35C's that popped the output MOSFETS and a 47K resistor. It is back on my bench and in full service again.
I was looking to buy one of these off ebay, so now I know Clive has given it the thumbs up (with caution) I am going to get one. Thanks Clive always useful info on your vids.
Thanks for doing this video! I was one of the requests in the last video to take a further look-see at this thing. Those of us on budget appreciate it : )
It's a nice power supply but has the usual pitfalls: 1. Poor leads. 2. Fan is a bit noisy. (Might be okay for some people) 3. Horrible output electrical noise. 4. Pulsating from an unstable feedback loop causing buzzing via Magnetostriction. 5. Crappy capacitors.
That's like saying it's a nice car except that you get horrible shakes at almost any speed, the wheels WILL come off in a week and it will propably burn you to death soonish... Where is the nice part?
6. The inrush limiting thermistors (hottest components) are mounted very close to the main smoothing capacitor. A bit more clearance would reduce the capacitor operating temperature. (A long term reliability issue.)
I've also heard that the insulated pins prevent things like neck chains that might sling low enough to bridge the connection while you're inserting at removing these plugs, especially if you're doing it behind something where you're reaching behind a cabinet or desk to do it.
Michael Beeny If they want to save copper (a bigger concern now than when the plug was invented), they can skimp on the tip of the pin that only does something during the brief moment of plugging it in or pulling it out. That tip could be hollow and filled with a plastic wedge (to push open the special British form of shutters). Ideally, such a wedge would be visible from the thin side of the pin so inspectors can see how deep it goes. Making this should be economically comparable to the current bad sleeving design.
That would mean a design change, which would require a designer and additional work for no reason, not gonna happen. After all the plugs go out and they get paid, who cares if some capitalist pig dies on the other side of the globe or not. And think how much metal they save when the pin can be thinner from the bottom!
If it's just a sleeve that covers the ground pin, while the pin itself goes all the way through to the plug, you could just cut the sleeve off and had a proper ground connection. But my bet is that the metal ground pin actually starts at the point where the sleeve ends, so if you were to cut that off, the pin would have nothing to sit in. That means, they saved a few tiny fractions of a penny because they used plastic instead of metal, where metal should have been used.
I've had 2 of these switch mode power supplies already and they do really great but whenever I've pushed them to their max current and voltage on an inductive load a small surface mount resistor close to the bridge rectifier ends up exploding. I would love to watch you abuse this thing and see if you get the same results before you took it apart.
Great review, Clive. I learned the crimp fail method on the cheap alligator test leads from Chiwan, too. Uncrimp and solder. My bench supply is the 305, a 5A model similar to the one you tested. I'm pulling that set of test leads off right now and soldering them, JIC. Thanks again. P.S: GAWD, I hate CCA wire! It's downright dangerous.
I bet I'm not the only person who watched this video and then went round their entire home, checking all the earth pins on their power leads. Thanks for the tip Clive. Luckily, I didn't find any.
If I recall sleeved line and neutral pins on plugs was also introduced to stop unpleasant people putting a 2p coin between the plug pins causing a dead short before the fuse when the socket was switched on. Also does the power switch inside have a red and black wire on it rather than two reds...
glad you pointed out the leads, after watching this i checked mine and saw theyre not stripped completely either and as im in USA the supply cord was fine but i put a more robust one on now anyway
I have one of these, and the thermistors failed catastrophically. I've been trying to find the their part numbers. Thanks to your well lit video, I was able to decipher them. Cheers
I saw the set screw (grub screw) you say to the black wire was tightened down onto the plastic outer insulation and not the wire itself. I always tin the wire when that type of connection is made on a power supply. The wire is much to small also
2:07 CLIVE I think you should do another video to remind people about the Shielded Earth Pin problem. The other day I saw a cheap double socket with a hole broken though the white plastic by the Earth socket .. something you might like to look into. btw.. this video popped up after watching you and the round roadworks light. I heard what you said that YT didn't like Vape videos.. Maybe you could just say about it this way... "Batteries that are found in metal tubes on the ground." Real question is.. I would like to put about 10 or 20 of the same sort in parallel.. I assume I need to equalise them first.. How? What is best way? Do I need a BMS. I would like to make a replacement 3.7v (old battery was 5000mA) for an older laptop.. When in parallel.. do I need a BMS?
Just checked mine -- a Lavolta rebrand, but otherwise looks identical -- and mu cable ends have been tinned and clamped to the screw properly. Mine also didn't come with the sheathed earth plug. Interesting. I wonder if a third shift made a cheaper one.
I brought one of the Lavolta branded units from Amazon, same unit design, but came with a UK complaint power lead, and the test leads were thicker core cable with soldered croc clips, and the banana plugs screwed onto the cable rather than the insulation.
I think mine's the same. Same brand name, at least, and I would have noticed if my leads were as nasty as the ones Clive's got there! Mine's only 5A, though, which has generally been enough for me thus far.
I have one of these power supplies. I don't regret buying it, but it does have issues with current regulation, and also when you adjust the voltage the current limit also changes significantly. The output is very noisy, and it is also sensitive to noise from the load. It does meet its power output claims, so if the feedback circuit was redesigned it would be a fairly nice power supply.
I wish they would run a safety campaign on TV regarding that type of plug, it bypasses the UK safety standards and is potentially hazardous ! I'm sure any insurance claim investigation would frown on the use of these and refuse to pay any compensation if they discovered they were the cause of any serious incident !
The way this one was purchased there was no inspection. You have to be careful buying directly from some of that countries suppliers. They will fool the customer in any way possible with no regrets.
I noticed on the 30V/5A version I purchased that the banana plugs weren't even secured with the grub screw properly. Lucky for me RadioShack recently had a big clearance sale and I got a few stackable banana plugs with soldered connections. That said, it's been a fairly solid supply so far, though I've mainly just used it for testing motors, recharging li-ion cells, and powering my Beaglebone Black, so nothing too terribly demanding load-wise.
When you said "affect directly" I heard in my head "Usage whether then right direct affect go out mosquito effect, for example sleep front bedroom not open lamp first use go out mosquito utensil, come up to suddenly turn off all lighting’s strong light 10-20 minute, or job, study shi ba mie mosquito utensil set free in dark place, all is very effective usage."
Now imagine, you grew up learing the Chinese alphabet, and then in grade school (primary school?) you leaarned the 'emperor's Chinese', and then you get to high school, and there is this really odd sounding language called 'English' that never is consistant with the rules for grammer, that have multiple sounding words meaning three different things, and have this awkward script with 26 symbols to it. now you wonder how things sound with english instructions to a Mandarin or Cantonese speaker. oh, never mind the other latin derived lanuages that have masculine, and feminine words. [access voice?] ~R.
Oh, and one more question, I am amazed at the evolution of modern welding equipment which now is using MOFSET among other items. I can't bring myself to understand how it can carry so much current...in some cases topping out at 300 amps and 25-30 volts at the TIG, MIG, or stick electrodes.....please explain.
Same here Im in the metal fab biz I cant bring myself to buy one with that stuff in one all mine have lead sled transformers in them Lincoln and Miller units .
Someone brought to my attention your video discussing the power supply that caught fire. It was of some concern as I bought a five amp model brand new some years ago and I've certainly loaded it up to near its maximum rating for many hours. The supply I've got is *completely* different inside (although externally, it looks nearly identical to this). It's a linear regulation design, with a conventional line frequency transformer and some control circuitry that switches taps on the transformer.
Hey Clive. Since I had my own melty moment (and a near house burning moment) with an off brand Chinese plugpack, I’ve carefully scrutinised each and every one I’ve got. However there was one that I recently received that I opened up and it actually looks ok, it looks to have really really good separation, my clueless eyes finding that the closest point between live and secondary side is the optoisolator, which looks appropriately sized. I’m wondering if I can send you photos for you to have a look at and see if it’s safe? Cheers
+Moon Moon The tracks often come close at the optoisolator. Even looking at a picture of the PCB I couldn't tell you if the separation in the transformer was good.
There are quite a few extremely cheap VFD's for sale now. Have to wonder if there is anything inside the case for the prices. They used to be mega dollars for a small one.
Would be nice to see a little heat shrink on the incoming mains and mains switch too? Just saw a wire poking upwards towards the other connection. Yikes!
I've got one similar to this, and as a cheap switch-mode bench PSU they are usable provided you understand the restrictions of the designs current limiting. One thing to look out for is the position of the foot on the rear left hand side - on mine the feet are held in with screws and that foot is directly underneath the mains input on the PCB - if it was screwed up too tight it would have 'interesting' results. Mine also arrived with the earth connection not soldered to the power input socket - so, like all chinese sourced electicals, you need to check the electrical safety before use.
maybe a handy tip; if you want to know what inductor is making the noise, take a screwdriver, put the point on the inductor and the handle to your ear... it works a bit like a stethoscope, and you can pinpoint the noise component that way :p be sure not to damage the insulation though ;)
If those test leads are the same ones I had, they're also CCA... I dead shorted them across a 15volt PSU, and didn't exceed the power supplies 15amp current limit...
Clive, have you tested the dodgy mains cable to see if the fuse is actually in circuit? We found one that still powered the device when the fuse was removed (a paractical joke that failed); when we cut the plug open, the wires went directly to the pins and the fuse holder was purely for decoration!
+CambridgeMart Not quite a practical joke. When stuff like that gets done intentionlly, and it results in death, then usually, someone has to answer to it. If if is a DEFECT in manufacture, where the employee of the factory assembled the part wrong , and the connector went into the molding (moulding) machine, and passed the QC check at the end of the line, then the problem batch needs to get corrected. Have you contacted the Manufacturer of the defective plug? Suppose, someone does not know about this dodgy connector, and buys the same apparatus, yet gets a letal shock, and dies becsuse of this error. Yes, I realize we cannot un-see things we have seen ,but here is a case of preventable problems later down the road.
I have one of these in the corner. In this one,that large choke wasn't even cable-tied down,and at some point,during shipping I suppose,it had moved so much that it broke the lead off of one of the resistors underneath it. It still worked fine,but it might be a good idea to fasten the choke down. The resistor wasn't terribly critical,the two resistors under the choke appear to be there just to give the supply a minimum load,if nothing is connected to the output.
On second look,it appears the choke was soldered down so that it hung out over the edge of the PCB a bit,and fouled the side of the case.. so that when the case was screwed in,it pushed the choke over,into the resistor,and snapped the lead off of the resistor.
Thank you Clive about the half covered earth pin warning! I have checked around our home and we have a few with ALL plastic earth pins that came with things like Alba phone chargers, Philips shavers and Amazon Fire tablet. Are these safe to use? Thanks very much, Neil.
Hi Clive. Thanks so much for the swift personal reassurance and for someone who hadn't subbed too! I didn't realise I never had. I've must have watched hundreds of your vids in the last year or two as they come up in my recommended and I find them thoroughly entertaining and fascinating, even though I have little knowledge in electronics, as you can tell by my question ;-) . My substitution oversight has now been rectified :-). Thanks again and keep up the good work. Neil.
I see people talking about soldering the test leads. I hope the mean the croc clip end. It is not good to solder stranded wire in a screwed terminal. The solder compresses and the connection comes loose. Maybe some types of terminal blocks are ok but it is still not the best way. Just twist it and fold it over once or twice to fit the barrel. Then tighten the screw. You can solder the wire in the barrel but the strands will suck up the solder and make a weak point where it bends.
maybe for the noise, responsible is the distance between the 30v-10A transformer and the big coil that might be too close for electromagnetic influences
I have one of these for rough powering of devices on my test bench, I noticed the current control buzzing and never used it since. Most of the time I only regulate voltage. Works fine.
A late thanks for this video! A few months back, when I was on a kit binge, I built up a variable output power supply, it came with all but a transformer to feed it with 24V AC. So I built it up and lay it aside on my bench, then came the big STOP BUYING! Order from my good wife of 50 years, and all purchases stopped. Well that lasted till I got pissed at something she bought that was useless, and it sort of pissed me off so I purchased a 24V DC Power supply. So I try to feed the DC to my PS and nothing. Tried reversing the polarity and nothing, I could trace some voltage to the board, but output was measurable, just, at about 0.03 V DC. So I think I probably blew it somehow as it had fallen from my bench and hit the damn carpet, where it spent weeks. Since I am still pissing the good wife off I decide to find a different front end for my new 24V DC supply, well I came upon the PS in this video, or at least an exact copy, the price was right at $9.99 US with free shipping from here in the USA! WOW what a deal for a 30 Volt 10 Amp variable PS! Hell YES I placed my order, then began to worry, but I figure I have enough crap laying around if it comes dead, I can fill it with parts and make my own in that case. I am awaiting the arrival with baited breath, and a chill down my spine as my wife will let me know about spending another 10 bucks of my own money.
I ended up ordering two of those damn things, one claimed it shipped, and was delivered to me in Texas. Well last time I lived in Texas was 1975, so a claim with Ebay and a refund. The next never came from China, that was months ago, and again a refund. So I had this 26 volt transformer that I picked up at a flea market for a quarter, the docs that came with the 24 volt PS that i built from a kit had in huge bold letters to never exceed 24 volts input or the device would be damaged. Well I figured the 24 V DC power supply I hooked to it did nothing so what do I have to loose. Hooked up the 26 V transformer, plugged her into the wall socket and I now have a nice adjustable V and A power supply that goes from 3 volts to 63 volts DC. I mounted it all in an old 3.5 inch plastic floppy case meant to hold 50 floppies, and it even looks kind of cool what with the digital display and the adjustment pots power switch and fan on the back to keep things kind of cool.
Needs some good old OFC (silicone-sleeved if you're feeling fancy) wire, and properly soldered connectors. It seems like this unit could have a chance at being somewhat decent for a cheap spare with a few modifications..
40 degrees is really not that bad... and also, screwing a wire down like that can actually create a great connection if done right. A screw can create a couple tons of clamping force.
zelja TM Anything is possible,,, and it would take someone that had no idea of what he was doing in order to do it that way...But hay,, Politicians do that every day. ... thanks for the reply...
i got a korad 2x30v power supply. it came with the same terrible leads. like 18 or smaller wire just pushed over in the connector. i replaced this with some 12ga silicone novak brand wire soldered into the jacks and to the clips. voltage drop before at 5A was like .5 volt or somewhere around there. and after it was like .02v or so. does anyone know where i can find various sizes of wire as flexible as the novak stuff? (novak hobby shop is no longer in business)
thank you clive, i never paid any attention to my plugs in my home until i seen this video, so i went around & found 3 of my plugs had a sleeve on the earth pin, all of which was a metal case appliance, now all the plugs are changed! thank you again clive!
It's good to live in a country with proper Schuko, where something like this can't happen. But, you almost are unable to unplug Schuko plugs... This is really annoying... They're so stiff!
The one advantage of the UK plug is the safety of it. Built in fuse, shuttering etc, although you can get those on the other regions units too, but they are only optional and not a standard like the UK plugs.
Will we ever see a world standardisation of plug sockets some day?
Taking the best features of each, or is it just too late for that?
Schuko also has shutters and safety. We don't need a fuse in each plug cause we don't need to have a 32 Amps ring mains cause we can actually afford copper. xP But as I said, it's hard to remove them out of sockets which really sucks and they aren't polarized... But also your UK ones are far too bulky...
Kyôdai Ken the worst part is when the Schuko plug rips the sockets out of the wall due to poor wall plate installation practices
@Allanda1 I never experienced that in Germany. But it happened to my ex gf back then after some years of tear on the same socket. I fixed it, though. It now can survive tanks pulling on it. ;)
The power MOSFET at the secondary side actually regulates the output linearly. The SMPS always delivers just a few more volts than what's the output voltage. Bench power supplies are usually built like this. This allows efficiency of a SMPS but also the supreme regulation ability of a linear regulator. So it is very efficient and yet it has very little ripple and very fast current limiting.
Great tip on the sheathed ground.
Had no idea about that, what a terrible design.
I come from the land of different plugs (not the type bigclive uses), but this really just seems like bad socket design. Can someone explain why the socket itself is only designed to contact half of the earth pin and not the entire length? (I'm guessing cost, but maybe something else?)
Duh... it is a faulty implementation by the Chinese as the man said.
linagee it's an illegal plug in UK. As Clive said it is the Chinese design that's wrong not the socket. A good plug don't need to be contacted for the entire length of the earth pin
@@linagee I think most electricians would say the UK has the best plug design in terms of safety and utility. The only real drawback is that it's very large, which is quite inconvenient.
"I saw a picture of one of these after it caught on fire, so I immediately ordered one!"
😱😱😂😂
Howdy Clive, I've been using a PSU similar to that one there for a few months now. Your vid motivated me to pop it open and have a look. Am I glad I did! The earth wire from the mains cable has a ring terminal on it, and the screw through that into the chassis was in by only three turns or so. Riiight. The terminal was flopping around on the screw. THANK YOU sir!
This reminds me of a control panel I saw at the local scrap yard, just a Chinese who-flung-dung machine cabinet with 3 ABB OEM VFDs inside (10 - 25 and probably 50Hp) and it looks like the crappy conductors they used to go into the 25HP drive got quite hot and started arcing, they probably were never torqued down to mfg specs either.
needless to say the whole panel was carbon black inside and all drives and PLC gear were destroyed by heat and smoke :(
You missed the other trick where the fuse is moulded into the plug and the red fuseholder cover pops out to reveal...plastic
To add; if you encounter illegal/ dangerous cable like that, don't throw it away. First, cut it near the base of the cable on the end that is faulty. Then throw it to trash. Don't let anyone think it is just thrown away and still works. It was hard to get used to that when i used my own cables to the death but really, protecting public is #1 priority. Destroy or disable dangerous equipment, don't rely on post-it-notes or memory or common sense. Even if it is marked "don't touch, will give you aids, ebola and explode" and it is in a trash, some moron will dig it out if it "looks alrite to me".. Take fuses out, cut cords, use hammers and saws.
Cut the illegal plug (from the cable) out replace it with a good plug.
@@supersaiyangoku3580 They still use very thin conductors in the cables with high resistance. I wouldn't use one personally.
When a piece of hardware is flakey, I try to loan it to someone I don't like.
If and when they complain about it I say "I don't know man, it was working ok before. You must have dropped it. That's an expensive piece of hardware, let me find out how much it costs".
Just a joke, I only did this once with a hard drive. I did not charge them.
I would not do this with a dangerous item.
Very nice post Clive. Lovely audio/ video quality too.
Another superbly informative video from Clive. I'm a retired professional electronic engineer, but I still learn something new from most of Clive's videos. I bought a similar, but not quite identical PSU from Amazon recently and was pleased to note that it doesn't have the same partially sleeved mains plug.
There is a subtle problem with the secondary small PSU in there. Does it have its own fuse? Probably not.. it means the large main fuse is protecting it. But this large fuse is too big for the secondary PSU. If this secondary PSU fails, the main fuse probably won't blow. Instead the secondary PSU catches fire, pops, smokes. Many PC power supplies have this same issue with their always on 5V "standby" supply.
You bring up a very good question.
The second or standby PSU, and what size fuse should protect the mains power cord from overload?
If the PSU is designed properly, there should be a link that will evaporate if 200% of the current is pulled for 1 second.
So, then is there a pico fuse in series with the mains voltage going to the alternate power supply. perhaps not.
Now all 'standby' PSUs need to be checked.
Lets have a Royal Enquiry!
must be Tony Blair's fault...... {lol).
I gotta admit, I watch your vids to fall asleep.
Same here at night
Me too. They are utterly relaxing.
Will Patterson got to admit that lm a little bit confused. Sometimes it seems to me that I'm just being used. Animals Pink Floyd.
Why am I watching a guy talk about a PSU at 3:30AM? I work in a bakery. I understand nothing.
HyDrolik
Insomnia?
HyDrolik you'll learn a lot with time!
Soon you'll be commenting about the shittyness of crappy LEDs!
Is that a picture of Gus?
Your right or left hand has a finger on it that clicked a button. Some garden scissors and a bit of jest should remove the source of the problems. Might have to repeat 9 times to achieve more robust results.
start with the leds chapter .
I bought a STP3010 (Sky Top Power) p/s just like this one, in Feb 2016. It had a fault (diode in the fan supply burnt out). Most likely from a track nearby touching a bit of solder under a filter cap. Easily fixed after the company gave me a portion of the circuit to look at.
Other than that, I tightened the binding post nuts (steel - naughty!), glued a bit of fibreglass pcb across the heatsinks so the they could be used to lift the whole pcb assembly. Put a warning note on the heatsinks (240V). Also positioned a business card so the fan drew more air from the heatsink area, and scraped the earth connection at the frame. And attached a handle for carrying. Checked output using 4 Ohm (bit if steel wire in a glass of water) periodically paralleled with 12 Ohm. No evidence of ringing on my (cheap) CRO. No problems since then.
thanks Clive !!!
también seguidor de big Clive? genial!
p.s : me encantan tus vídeos seguí asi!!!
Better than the heatsink compound trick is a UV reactive dye and blacklight.
What I use was originally meant for crack detection of some kind and looks like a crayon however it contains a bright orange/red UV reactive dye.
You basically rub the crayon over a surface and shine a UV torch on it and the lettering lights up (and any surface imperfections/cracks). The crayon itself is normally enough on it's own (it's a light colour) however the UV light makes it completely visible no matter the lighting conditions (it also allows pictures to be taken very easily as the lettering actually emits light).
Yep, as I guessed on the last video: the connector gets very hot because of chincy plugs and wires.
Overall the circuit doesn't look bad. Line filtering, chunky components and heatsinks, thermal cutout are nice. Seems to be a proper design (except for the weird thing with the current regulation).
The overall build quality lets it down again though. Crooked components, big inductor only "secured" with a zip tie, one of the front panel wires so short it tugs on the connector, bad connections to the binding posts (at least some here have reported that) and of course the really dangerous wires they supplied with it (both of them, mains and secondary).
Given the price this is a PSU that beginners will buy, who at the same time very likely will not know how to spot a dangerous product and how to fix it. That's worrying.
superdau
In the zip ties defense, a lot of modern cars have them holding the wiring looms together/in place. Chrysler loves em as I'm sure some others do. If they can handle the heat/cold cycles and vibration of the engine and road, I'd think an inductor is little worry. But how you use them is just as important as where you use them.
I mean, the mounting isn't great, really shouldn't be a big deal for something that hides in the corner of a bench.
superdau any suggestions for the best balance of budget/without being unsafe for beginners
superdau actually I’m just getting to the end of the video, is there a couple of mods that can be done that would make this unit decent? Forgive me I don’t entirely understand all the lingo but will learn whatever needed to make appropriate mods. I caught the bit about soldering the leads, but looks like I missed some others
I got sent one of those bastard mains cables from ebay. The resistance of each conductor is over 1 ohm - should be milli-ohms, they are DANGEROUS
ForestCat_Peter
"I got sent one of those bastard mains cables from ebay. The resistance of each conductor is over 1 ohm - should be milli-ohms, they are DANGEROUS"
Why not tell Trading-Standards? Of course it depends where it was sent-from. If from a seller in the UK, they need a roasting. Perhaps placed handcuffed to a chair surrounded by a number of their devices that are set to self-destruct with such dodgy mains leads.
If from abroad, say via Ebay or Amazon, then they need to crack-down on the sellers, but there's not much else TS can do with overseas suppliers.
Never will understand why test eqpt companies skimp on leads. We just paid several thousand pounds for an 8 1/2 digit bench multimeter for our lab at work from a very reputable British manufacturer. The meter itself is top-notch. The leads that came with it were about as good as the ones seen here. Luckily we use our own in-house made leads anyway.
I had never seen that heat sink compound trick. Made this video worth a lot. Cool! Thanks to Dave at the EEVBlog!
Thank you. I think I have this power supply and will check on the leads and the mains cable. It is amazing how a device can be made so vulnerable by these leads and the supply cord - which I will check. I often use my own power leads.
Great point about the sleeved PE... that's insane!
Was doing a bit of electrolysis on some old tools with the exact same power supply. For once I moved all outside to avoid any building up of hydrogen in the workshop and it was a good thing. I'm guessing about 10 minutes in I was greeted with a full on fire 7 feet tall just managed to pull the plug and dumped the bucket of electrolysis solution tools and all before my went up. Being one with a guilty conscience I just assumed that I did something stupid and most times that is a safe bet. Just looked at the burned remains of it. The control panel is melted and hanging open and can see no damage on the inside and very little damage on the backside of the control panel so yes I believe you are %100 correct about the connectors on the front. I've been a subscriber of yours long before I almost burned my house down and watch plenty of UA-cam videos before buying this power supply and still some how overlooked this vid
Thanks Clive. Bought one of these off eBay from a UK supplier and the mains lead has the same earth pin problem. Will change this before I use it.
If stuff catches fire on itself you can bet your ass Big Clive will order it!
EpicLPer I smell a get rich quick scheme brewing! 😂
so my mom starts on fire will he buy her on the black market?
anefyon yes
Seen it burning merrily on The Tube? MUST buy one!! :-D
electronics that self-ignite are clive bait.
Clive, have you ever had a look at a PSU for a desktop computer? I tried searching the channel, but didn't see one. Popular wisdom in the PC building community is that you should never cheap out on your power supply. Anecdotes I have read include: they'll fry your other components, electrocute anyone who touches the case, blow up under moderate usage, or set your house afire. I'd be interested to know if there's truth to that. I'm sure there are cheap, shitty ATX power supplies from China, just waiting to unleash hell...
There really is NOTHING WORSE than copper-coated aluminium.
Tom Straight aluminium. I've got some at home and its useless since you can't solder to it.
Don't they use aluminum for all the heavy duty power lines?
Bubonic plague?
That is a fun thing to learn the hard way lol. Making prototypes of stuff figure hey aluminum foil could take an option I didn't have place... nope lol. I have solder nickels and pennies together solder sculpting with crap solder yet aluminum foil is quite rude.
Evil from evolution
I`ve seen as much aluminum wire stolen as copper they both fetch a good price at recyclers
I have one. It failed quite spectacularly due to a bad IRF840. There was a dramatic jump in stability after the repair. It started to go into thermal runaway when the fet popped. If I hadn't been there, it would have been a disaster. NOTE: replace the fine voltage pot. A bad run of them was used on this model! I used a 10 turn precision pot and now setting this beast no longer pisses me off.
Glad I saw this. This is the power supply I bought as I am a beginner with electronics and the price was tenable. I had my doubts but I'm glad to see at least the power supply itself is robust.
I use a ceramic screw driver for all kinds of trimmers. It reduces the influence on the circuit and is a added safety for me.
Excellent video Clive. I love your teardowns and reviews. One learns a lot from you. I always undo my cables also. The ones that are screwed in I always twist, fold then solder to make sure that the screw bites in solidly. I know that the solder has a low melting point but I figure that there would be less resistance in the connection this way and therefore a lower chance of the banana plugs heating up.
It is not good to solder stranded wire in a screwed terminal. The solder compresses and the connection comes loose. Maybe some types of terminal blocks are ok but it is still not the best way.
A couple of cow orkers where I used to work did this on a junction box for a hydraulic pump and the wires came loose with the vibration. This caused an emergency shut down on the gas turbine which is not a nice thing to do.
Thanks for this video Clive! I have a similar PSU and re-soldered the leads but before I did that I checked the resistance with my Fluke 23 at about 0.9 ohms. After modifying the leads the resistance was a more sensible 0.2 ohms.
Thanks Clive, came to this a bit late. Have a Lavolta model of this PSU and happy to report the cables are Good. Mains plug full earth pin and output cables all soldered connections to the crocks and the end of the cable is solder tinned and clamped. Wire is very thick and difficult to bend. Had a fault where the protection diode across the output went S/C so had replace that.
Great advice on those earth prongs, I would not have known that was an issue.
I found the 'convenient' spinny feature on the banana plug to just lose continuity, so I had to solder across the slip-ring. To do this, once you take out the set-screw, the plastic piece just slides off, making for easily soldering the metal part, and losing all the pieces. Then for the lead wire, something like 18 awg or 1mm, folded back onto itself 3 times and twisted, then tin it (make it shiny with solder), allowed the screw to dig in and make a nice connection regardless of radial orientation. Thanks for the video!
Thanks for the bit about testing for copper coated aluminium. I retired as an electronics tech from the US Navy in '93 and I don't remember that particular trick in our training, but then again I guess most of our stuff was procured under pretty tight contract overview so I don't think we would have run into it very often.
Copper coated aluminium and other non-copper flexes are a fairly recent thing. Purely to cut costs.
Very interesting point about the insulated earth pin and something I had not realized or looked out for before, on a related point I recently bought a Chinese aquarium heater which came with a UK style square pin molded plug which looked strange because it was very small, but fitted the socket OK, however the plug did not have a fuse or facility to fit one. "UK plug" looks like a reason to buy on Ebay, but non compliant UK plug , probably not.
I have one of these supplies. I had trouble with heat and found the terminal back plate was not tight enough. I also ran a SSTC at 31 volts and nearly 10 amps via two TIP35C's that popped the output MOSFETS and a 47K resistor.
It is back on my bench and in full service again.
I was looking to buy one of these off ebay, so now I know Clive has given it the thumbs up (with caution) I am going to get one. Thanks Clive always useful info on your vids.
I wouldn't recommend this one. Try and get a bench PSU from a local mail order components company.
Great tip on determining cable quality in the end. Thank you.
Thanks for doing this video! I was one of the requests in the last video to take a further look-see at this thing. Those of us on budget appreciate it : )
It's a nice power supply but has the usual pitfalls:
1. Poor leads.
2. Fan is a bit noisy. (Might be okay for some people)
3. Horrible output electrical noise.
4. Pulsating from an unstable feedback loop causing buzzing via Magnetostriction.
5. Crappy capacitors.
That's like saying it's a nice car except that you get horrible shakes at almost any speed, the wheels WILL come off in a week and it will propably burn you to death soonish... Where is the nice part?
petti78 It was a Holden?
The nice part is it'll sit nicely in a bin... :)
Feel free to purchase a £150-£200 PSU instead of paying £40.
6. The inrush limiting thermistors (hottest components) are mounted very close to the main smoothing capacitor. A bit more clearance would reduce the capacitor operating temperature. (A long term reliability issue.)
I've also heard that the insulated pins prevent things like neck chains that might sling low enough to bridge the connection while you're inserting at removing these plugs, especially if you're doing it behind something where you're reaching behind a cabinet or desk to do it.
As much as these Chinese companies love saving money, you'd think they would quit wasting plastic on sleeving those ground pins.
Plastic is cheaper than metal. Safety does not come high on the agenda in China, life is cheap.
Michael Beeny plastic on top of metal is not cheaper than just metal though.
Michael Beeny If they want to save copper (a bigger concern now than when the plug was invented), they can skimp on the tip of the pin that only does something during the brief moment of plugging it in or pulling it out. That tip could be hollow and filled with a plastic wedge (to push open the special British form of shutters). Ideally, such a wedge would be visible from the thin side of the pin so inspectors can see how deep it goes. Making this should be economically comparable to the current bad sleeving design.
That would mean a design change, which would require a designer and additional work for no reason, not gonna happen. After all the plugs go out and they get paid, who cares if some capitalist pig dies on the other side of the globe or not. And think how much metal they save when the pin can be thinner from the bottom!
If it's just a sleeve that covers the ground pin, while the pin itself goes all the way through to the plug, you could just cut the sleeve off and had a proper ground connection. But my bet is that the metal ground pin actually starts at the point where the sleeve ends, so if you were to cut that off, the pin would have nothing to sit in. That means, they saved a few tiny fractions of a penny because they used plastic instead of metal, where metal should have been used.
I've had 2 of these switch mode power supplies already and they do really great but whenever I've pushed them to their max current and voltage on an inductive load a small surface mount resistor close to the bridge rectifier ends up exploding. I would love to watch you abuse this thing and see if you get the same results before you took it apart.
Great review, Clive. I learned the crimp fail method on the cheap alligator test leads from Chiwan, too. Uncrimp and solder. My bench supply is the 305, a 5A model similar to the one you tested. I'm pulling that set of test leads off right now and soldering them, JIC. Thanks again. P.S: GAWD, I hate CCA wire! It's downright dangerous.
I bet I'm not the only person who watched this video and then went round their entire home, checking all the earth pins on their power leads. Thanks for the tip Clive. Luckily, I didn't find any.
8:18 Bipolar junction transistor, not unijunction.
Why are you thinking about UJTs, Clive?
+Godfrey Poon Not sure why I said that. So many transistors in the heat of the moment.
+bigclivedotcom Don't worry Clive, it certainly wasn't a _base_ less mistake.
heh heh
*facepalm* Good one!
ha ha wow
A manically depressed trans-sister?
If I recall sleeved line and neutral pins on plugs was also introduced to stop unpleasant people putting a 2p coin between the plug pins causing a dead short before the fuse when the socket was switched on.
Also does the power switch inside have a red and black wire on it rather than two reds...
glad you pointed out the leads, after watching this i checked mine and saw theyre not stripped completely either and as im in USA the supply cord was fine but i put a more robust one on now anyway
Greagans Favor While chinesium US plugs may not have the sleeve problem, all the other stuff could still be dead wrong.
I have one of these, and the thermistors failed catastrophically. I've been trying to find the their part numbers. Thanks to your well lit video, I was able to decipher them. Cheers
I'd like to see your thoughts on whats inside of a 1.2Kw Server Powersupply.
You can pick them up fairly cheap, about 20 bucks AUD if you go hunting.
I saw the set screw (grub screw) you say to the black wire was tightened down onto the plastic outer insulation and not the wire itself. I always tin the wire when that type of connection is made on a power supply. The wire is much to small also
So, circuit-wise it is basically an old-style ATX power supply...
Yes, and I'll bet the switchers are actually BJTs as well (13009 or similar, as usual in the old half-bridge arrangement).
apart from the multi voltage outputs
which the bench psu doesn't
2:07 CLIVE I think you should do another video to remind people about the Shielded Earth Pin problem.
The other day I saw a cheap double socket with a hole broken though the white plastic by the Earth socket ..
something you might like to look into.
btw.. this video popped up after watching you and the round roadworks light.
I heard what you said that YT didn't like Vape videos..
Maybe you could just say about it this way...
"Batteries that are found in metal tubes on the ground."
Real question is..
I would like to put about 10 or 20 of the same sort in parallel.. I assume I need to equalise them first.. How? What is best way?
Do I need a BMS.
I would like to make a replacement 3.7v (old battery was 5000mA) for an older laptop..
When in parallel.. do I need a BMS?
Thanks for answering my question in the latest livestream 😻
Just checked mine -- a Lavolta rebrand, but otherwise looks identical -- and mu cable ends have been tinned and clamped to the screw properly. Mine also didn't come with the sheathed earth plug. Interesting. I wonder if a third shift made a cheaper one.
Clive, you nailed it, dam bad connections.
Otherwise not a bad supply.
It's 1:05 am and I suddenly feel compelled to go and check every electrical device in my house for a sleeved earth pin...
I brought one of the Lavolta branded units from Amazon, same unit design, but came with a UK complaint power lead, and the test leads were thicker core cable with soldered croc clips, and the banana plugs screwed onto the cable rather than the insulation.
I think mine's the same. Same brand name, at least, and I would have noticed if my leads were as nasty as the ones Clive's got there! Mine's only 5A, though, which has generally been enough for me thus far.
I have one of these power supplies. I don't regret buying it, but it does have issues with current regulation, and also when you adjust the voltage the current limit also changes significantly.
The output is very noisy, and it is also sensitive to noise from the load. It does meet its power output claims, so if the feedback circuit was redesigned it would be a fairly nice power supply.
Lots of great info here Clive! Thanks. I've never seen aluminum wire under a "flame test". How terrible is that?!?!
Interesting bit about the earth connection on the plug. Need to spend the weekend checking all my dodgy Chinesium cables.
I wish they would run a safety campaign on TV regarding that type of plug, it bypasses the UK safety standards and is potentially hazardous ! I'm sure any insurance claim investigation would frown on the use of these and refuse to pay any compensation if they discovered they were the cause of any serious incident !
The way this one was purchased there was no inspection.
You have to be careful buying directly from some of that countries suppliers.
They will fool the customer in any way possible with no regrets.
"said the whole front was on fire" - so I immediately ordered one. LOL
Nice xkcd profile picture.
Another great video thanks Big Clive!
How did you get that power supply for £1?
He has a membership at Poundland, you pay £300 a week and everything you buy is a pound.
I noticed on the 30V/5A version I purchased that the banana plugs weren't even secured with the grub screw properly. Lucky for me RadioShack recently had a big clearance sale and I got a few stackable banana plugs with soldered connections.
That said, it's been a fairly solid supply so far, though I've mainly just used it for testing motors, recharging li-ion cells, and powering my Beaglebone Black, so nothing too terribly demanding load-wise.
When you said "affect directly" I heard in my head "Usage whether then right direct affect go out mosquito effect, for example sleep front bedroom not open lamp first use go out mosquito utensil, come up to suddenly turn off all lighting’s strong light 10-20 minute, or job, study shi ba mie mosquito utensil set free in dark place, all is very effective usage."
Someone has been reading the 'Chinglish' instruction manuals ! LOL
RichardMJ R totally because I heard it in Clives voice. Lol gotta love the bug and people zapper. Haha
Now imagine, you grew up learing the Chinese alphabet, and then in grade school (primary school?) you leaarned the 'emperor's Chinese', and then you get to high school, and there is this really odd sounding language called 'English' that never is consistant with the rules for grammer, that have multiple sounding words meaning three different things, and have this awkward script with 26 symbols to it.
now you wonder how things sound with english instructions to a Mandarin or Cantonese speaker.
oh, never mind the other latin derived lanuages that have masculine, and feminine words.
[access voice?]
~R.
Oh, and one more question, I am amazed at the evolution of modern welding equipment which now is using MOFSET among other items. I can't bring myself to understand how it can carry so much current...in some cases topping out at 300
amps and 25-30 volts at the TIG, MIG, or stick electrodes.....please explain.
Same here Im in the metal fab biz I cant bring myself to buy one with that stuff in one all mine have lead sled transformers in them Lincoln and Miller units .
Someone brought to my attention your video discussing the power supply that caught fire. It was of some concern as I bought a five amp model brand new some years ago and I've certainly loaded it up to near its maximum rating for many hours.
The supply I've got is *completely* different inside (although externally, it looks nearly identical to this). It's a linear regulation design, with a conventional line frequency transformer and some control circuitry that switches taps on the transformer.
Hey Clive. Since I had my own melty moment (and a near house burning moment) with an off brand Chinese plugpack, I’ve carefully scrutinised each and every one I’ve got. However there was one that I recently received that I opened up and it actually looks ok, it looks to have really really good separation, my clueless eyes finding that the closest point between live and secondary side is the optoisolator, which looks appropriately sized.
I’m wondering if I can send you photos for you to have a look at and see if it’s safe? Cheers
+Moon Moon The tracks often come close at the optoisolator. Even looking at a picture of the PCB I couldn't tell you if the separation in the transformer was good.
BigClive replacing the power supply power cord and better set test leads I think this would nice little power supply ,
Thanks for another great video
There are quite a few extremely cheap VFD's for sale now. Have to wonder if there is anything inside the case for the prices. They used to be mega dollars for a small one.
Would be nice to see a little heat shrink on the incoming mains and mains switch too?
Just saw a wire poking upwards towards the other connection. Yikes!
I've got one similar to this, and as a cheap switch-mode bench PSU they are usable provided you understand the restrictions of the designs current limiting.
One thing to look out for is the position of the foot on the rear left hand side - on mine the feet are held in with screws and that foot is directly underneath the mains input on the PCB - if it was screwed up too tight it would have 'interesting' results.
Mine also arrived with the earth connection not soldered to the power input socket - so, like all chinese sourced electicals, you need to check the electrical safety before use.
maybe a handy tip; if you want to know what inductor is making the noise, take a screwdriver, put the point on the inductor and the handle to your ear... it works a bit like a stethoscope, and you can pinpoint the noise component that way :p
be sure not to damage the insulation though ;)
If those test leads are the same ones I had, they're also CCA... I dead shorted them across a 15volt PSU, and didn't exceed the power supplies 15amp current limit...
Oh that's really crap
Clive, have you tested the dodgy mains cable to see if the fuse is actually in circuit? We found one that still powered the device when the fuse was removed (a paractical joke that failed); when we cut the plug open, the wires went directly to the pins and the fuse holder was purely for decoration!
+CambridgeMart Not quite a practical joke. When stuff like that gets done intentionlly, and it results in death, then usually, someone has to answer to it.
If if is a DEFECT in manufacture, where the employee of the factory assembled the part wrong , and the connector went into the molding (moulding) machine, and passed the QC check at the end of the line, then the problem batch needs to get corrected.
Have you contacted the Manufacturer of the defective plug?
Suppose, someone does not know about this dodgy connector, and buys the same apparatus, yet gets a letal shock, and dies becsuse of this error.
Yes, I realize we cannot un-see things we have seen ,but here is a case of preventable problems later down the road.
Good safety critique. Many thanks.
I have one of these in the corner. In this one,that large choke wasn't even cable-tied down,and at some point,during shipping I suppose,it had moved so much that it broke the lead off of one of the resistors underneath it. It still worked fine,but it might be a good idea to fasten the choke down. The resistor wasn't terribly critical,the two resistors under the choke appear to be there just to give the supply a minimum load,if nothing is connected to the output.
On second look,it appears the choke was soldered down so that it hung out over the edge of the PCB a bit,and fouled the side of the case.. so that when the case was screwed in,it pushed the choke over,into the resistor,and snapped the lead off of the resistor.
I usually snap the earth pins off those dodgy mains leads just in case someone picks them up and tries to use them.
I bury them on Mull at a number of grid co-ordinates.
Thank you Clive about the half covered earth pin warning! I have checked around our home and we have a few with ALL plastic earth pins that came with things like Alba phone chargers, Philips shavers and Amazon Fire tablet. Are these safe to use? Thanks very much, Neil.
The all plastic ones are fine. They're used with double insulated products as a key to open the socket shutters.
Hi Clive. Thanks so much for the swift personal reassurance and for someone who hadn't subbed too! I didn't realise I never had. I've must have watched hundreds of your vids in the last year or two as they come up in my recommended and I find them thoroughly entertaining and fascinating, even though I have little knowledge in electronics, as you can tell by my question ;-) . My substitution oversight has now been rectified :-). Thanks again and keep up the good work. Neil.
I see people talking about soldering the test leads.
I hope the mean the croc clip end.
It is not good to solder stranded wire in a screwed terminal. The solder compresses and the connection comes loose. Maybe some types of terminal blocks are ok but it is still not the best way. Just twist it and fold it over once or twice to fit the barrel. Then tighten the screw.
You can solder the wire in the barrel but the strands will suck up the solder and make a weak point where it bends.
Had similar issues with my 30v/5a, out of the box banana plugs got hot at anything > 2 amps.
Ooh the flame test just changed my life.
Thanks Clive both interesting and a welcome safety warning.
maybe for the noise, responsible is the distance between the 30v-10A transformer and the big coil that might be too close for electromagnetic influences
I have one of these for rough powering of devices on my test bench, I noticed the current control buzzing and never used it since. Most of the time I only regulate voltage. Works fine.
Thanks for showing how to spot a bogus mains cable!
A late thanks for this video! A few months back, when I was on a kit binge, I built up a variable output power supply, it came with all but a transformer to feed it with 24V AC. So I built it up and lay it aside on my bench, then came the big STOP BUYING! Order from my good wife of 50 years, and all purchases stopped. Well that lasted till I got pissed at something she bought that was useless, and it sort of pissed me off so I purchased a 24V DC Power supply. So I try to feed the DC to my PS and nothing. Tried reversing the polarity and nothing, I could trace some voltage to the board, but output was measurable, just, at about 0.03 V DC. So I think I probably blew it somehow as it had fallen from my bench and hit the damn carpet, where it spent weeks. Since I am still pissing the good wife off I decide to find a different front end for my new 24V DC supply, well I came upon the PS in this video, or at least an exact copy, the price was right at $9.99 US with free shipping from here in the USA! WOW what a deal for a 30 Volt 10 Amp variable PS! Hell YES I placed my order, then began to worry, but I figure I have enough crap laying around if it comes dead, I can fill it with parts and make my own in that case. I am awaiting the arrival with baited breath, and a chill down my spine as my wife will let me know about spending another 10 bucks of my own money.
I ended up ordering two of those damn things, one claimed it shipped, and was delivered to me in Texas. Well last time I lived in Texas was 1975, so a claim with Ebay and a refund. The next never came from China, that was months ago, and again a refund. So I had this 26 volt transformer that I picked up at a flea market for a quarter, the docs that came with the 24 volt PS that i built from a kit had in huge bold letters to never exceed 24 volts input or the device would be damaged. Well I figured the 24 V DC power supply I hooked to it did nothing so what do I have to loose. Hooked up the 26 V transformer, plugged her into the wall socket and I now have a nice adjustable V and A power supply that goes from 3 volts to 63 volts DC. I mounted it all in an old 3.5 inch plastic floppy case meant to hold 50 floppies, and it even looks kind of cool what with the digital display and the adjustment pots power switch and fan on the back to keep things kind of cool.
Needs some good old OFC (silicone-sleeved if you're feeling fancy) wire, and properly soldered connectors. It seems like this unit could have a chance at being somewhat decent for a cheap spare with a few modifications..
151,151 views?!
edit: ty clive for hearting my comment, first heart i got ever in UA-cam, thank you and keep doing good content.
So much GOOD information in this video.
Could you do a heat test (for the leads) with proper ones please?
For some reason I get adverts for fire extinguishers.
Maybe they (the advertisers) sense dangerous ideas and want to protect you.
I once used the flame test to illustrate the difference in quality between cca and solid copper Ethernet cable
40 degrees is really not that bad... and also, screwing a wire down like that can actually create a great connection if done right. A screw can create a couple tons of clamping force.
Good job,,
Could the plastic be scraped off of the earth pin???
Willy Bee I guess pin IS plastic, and only the tip is fully metal.
zelja TM
Anything is possible,,, and it would take someone that had no idea of what he was doing in order to do it that way...But hay,, Politicians do that every day. ... thanks for the reply...
Good tip about the sleeved earth, didn't know that.
i got a korad 2x30v power supply. it came with the same terrible leads. like 18 or smaller wire just pushed over in the connector.
i replaced this with some 12ga silicone novak brand wire soldered into the jacks and to the clips. voltage drop before at 5A was like .5 volt or somewhere around there. and after it was like .02v or so.
does anyone know where i can find various sizes of wire as flexible as the novak stuff? (novak hobby shop is no longer in business)